Keyboard device



May 3, 1966 o. T. WOOD ETAL KEYBOARD DEVICE Inventors Orville T. wood B Julius E. Underwood Jr. AL! A m Afiy Filed Oct. 6, 1964 mm Hm .M m

United States Patent 3,248,992 KEYBOARD DEVICE ()rville T. Wood and Julius E. Underwood, Jr., Essex, Conn., asisgnors to Pratt, Read & (10., Ivoryton, Conn., a corporation of Connecticut Filed Oct. 6, 1964, Ser. No. 401,929 7 Claims. (Cl. 84436) This invention relates to musical keyboard instruments, and more particularly to a key pin bushing for a key in such an instrument.

Keys for musical keyboard instruments are often pivoted on or guided by a key pin which extends upwardly from a frame into an opening in the key. Such key pins may, for example, be used in the balance rail of a keyboard instrument to permit the key to pivot vertically thereon while holding the key oriented in the horizontal plane. Another use for a key pin is at the front of the keys wherein the key pin extends upwardly from a key frame into an opening in the front of the key in order to guide the key in proper vertical alignment. In either case, some type of bushing lbetween the key pin and the key itself is desirable to reduce noise and to provide a smooth feel or touch to the musician playing the keyboard instrument.

Heretofore such bushings have been commonly of felt or similar cloth material. Such cloth bushings have certain disadvantages, however, including the fact that they are susceptible to temperature and humidity changes and are diificult of installation and replacement.

Accordingly, it is an object of this invention to provide an improved key pin bushing for a key in a musical keyboard instrument.

Another object of this invention is to provide a key pin bushing for a key in a musical keyboard instrument, which bushing is capable of being mass produced, easy to install and replace, and is not susceptible to changes in temperature and humidity.

A feature of the invention is the provision of a bushing comprising a hollow cylindrical body of generally oval cross section with a plurality of ridges extending at least partially along a cross sectional circumference of the bushing and being disposed axially on the outer surface thereof.

Another feature of the invention is the provision of a key pin bushing molded of low friction plastic in a unitary piece, and which comprises a hollow cylindrical body of generally oval cross section having oppositely disposed relatively narrow sides and oppositely disposed relatively wide sides, with the narrow sides having a plurality of transverse ridges placed axially along the outer surface thereof.

Still another feature is the provision of glue nubs bonded to the walls of a cylindrical opening in a wooden key shank and securing a plastic key pin bushing in the opening by mechanically engaging transverse ridges on the bushing.

FIG. 1 is a full section elevational view of a natural key incorporating key pin bushings constructed in accordance with the invention, and with an alternative position of the key shown in phantom;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1;

FIG. 4 is an enlarged elevational view of the bushing of FIG. 2 in place, with the key in section;

FIG. 5 is a bottom view of the bushing of FIG. 4;

FIG. 6 is an end elevational view of the bushing of FIG. 4; and

Patented May 3, 1966 FIG. 7 is an enlarged elevational view of the bushing of FIG. 3 in place, with the key in section.

In accordance with the invention, a key pin bushing for a key in a musical keyboard instrument is molded of low friction plastic in a unitary piece. The bushing comprises a hollow cylindrical body of generally oval cross section. An outwardly extending flange portion is provided at one end of the body, and a plurality of ridges are spaced axially on the outer surface of the body. These ridges extend at least partially along a cross sectional circumference thereof to provide means for securing the bushing in an opening in a key without the necessity for adhesion between the bushing and the key. Such securing is accomplished by glue nubs bonded to the walls of the opening and mechanically engaging the ridges. The ridges may be comprised of integral fins extending outwardly of the hollow cylindrical body or they may be provided by the portion of the bushing between a plurality of grooves formed on the sur- (face of the body.

FIG. 1 illustrates a key incorporating a bushing constructed in accordance with the invention. The key 11 is pivotal at a balance rail 12, which rail has a key pin 13 extending upwardly therefrom, a felt pad 14 surrounds pin 13 and is disposed between the bottom of key 11 and the top of balance rail 12.

Key 11 is provided with means to permit the pivoting of the key in a vertical plane on pin 13, and to prevent movement thereof with respect to the balance rail 12 in a horizontal plane. Such means include an opening 15, which has cylindrical walls and which is substantially oval in cross section. Opening 15 extends downwardly from the top of key 11, terminating near the bottom of the key. A circular hole 16 is provided from the bottom of key 11 into the opening 15, and key pin 13 extends upwardly through this hole. Key 11 may pivot about pin 13 to the position shown in phantom as 11a. To steady key 11 in its pivotal movement about pin 13, a bushing 21 is provided. As may be seen more clearly in FIG. 2, bushing 21 is comprised of a hollow cylindrical body 22 of generally oval cross section. An outwardly extending flange portion 23 is disposed at one end of body 22 and lies against the top surface of key 11, the outer diameter of the flange portion being greater than the diameter of the opening 15. The minor inner diameter of body 22 is such as to mate with the pin 13 and provide a cushioning engagement therebetween. Such engagement prevents any rattling of the key and also provides a particular touch or feel for the musician playing the keyboard instrument.

The front of key 11 is guided in a similar fashion by means of a'key pin 25 extending upwardly from the front of key frame 26. A felt pad 27 surrounds the base of pin 25 adjacent key frame 26 to prevent noise. Pin 25 extends upwardly into a cylindrical opening 28 of generally oval cross section. A bushing 31 having a flange 32 is included in the opening 28 and performs substantially the same function as bushing 21 did in connection with pin 13. Referring particularly to FIG. 3, it may be seen that the minor inner diameter of bushing 31 is such that the walls of the bushing engage the pin 25 with a cushioning effect for providing guidance and preventing rattling.

Heretofore, bushings such as bushings 21 and 31 were often made of felt or similar cloth material. Felt however, is often subject to wear and may change characteristics, including its size and coefficient of friction, considerably with changes in temperature and humidity. The invention contemplates the manufacture of abushing out of a unitary piece of plastic, preferably a low friction plastic. Such plastic materials may be obtained in formulations which, when mold cured, are not as hard as the wood of the key and therefore help to cushion with a relatively low level of noise against bumping oi the metal key pin. The plastic may be pigmented to simulate the color of more traditional felt or cloth bushings. A preferred material for the bushings of the invention is ethylene-vinal acetate c-opolymer, such as is available from Us. Industrial Chemicals Company under the designation Ultrathene. Other materials might also be used, such as rubber or silicone copolymers, tetrafluoroethylene, or fluorocarbon.

Certain of these low friction plastic materials may be difiicult to bond or glue with any of the common bonding agents, glues or cements. To alleviate this problem, three small fins are provided at each of the narrow ends of the bushing 21. These fins 33 (FIGS. 4, 5 and 6) are spaced axially along the outer surface of the body 22 at the oppositely disposed relatively narrow sides thereof. Pins 33 extend at least partially along a cross sectional circumference of body 22 and, as seen in FIG. 6, the chordal distance across the outer ends of fins 33 is less than the minor outer diameter of body 22. These fins 33 form ridges and the tip to tip distance between the oppositely disposed ridges is equal to the major diameter of opening 15. A glue with filling characteristics, such as polyvinyl chloride glue, is applied to the ends of the molded piece or to the ends of the opening in the key 11 at the time of assembly of the molded plastic bushing into the key. When the glue hardens, even though it will not bond to the molded plastic material, it will bond to the wood and form nubs of glue 34 which interlock mechanically with the ridges at the ends of the plastic bushing. These nubs of glue 34 will adhere to the wood key sufliciently to survive several removals and insertions of molded plastic bushings, facilitating field replacement of the bushings. In the event the nubs of glue 34 are destroyed, re-assernbly including replacement of the glue is still a relatively simple operation, compared with assembling the more traditional felt type bushings.

The long side walls of the molded plastic bushing tend to lay inwards firmly and gently against the sides of the metal key pins, thus providing a cushioning effect against side pressure on the key without building up excessive friction between the bushing and the key pin. The low coeflicient of friction of the surface of the plastic bushing contributes to this desirable result.

Bushing 31 utilizes an alternative construction for the ridges at the narrow sides of the bushing. Ridges 35 (FIG. 7) are formed by the bushing material between grooves 36 in the outer surface of the bushing. In the case of bushing 31, the dimension over the tips of ridges 35 is still the same as the dimension of opening 28. Bushings 21 are secured in opening 28 by nubs of glue 34 similar to those used to secure bushing 21 in opening 15.

A further advantage of bushings constructed in accordance with the invention is that the inherent memory or resiliance of the molded plastic facilitates an easing operation sometimes performed on key pin openings in wood keys. This easing operation basically consists of squeezing the wood and bushing material on each side of the opening between jaws of special pliers, so as to compress the wood slightly. This results in making the openings slightly more open on the key pin. This is sometimes necessary because all piano and organ manufactgrers do not agree on the desirable amount of clearance or freedom between the bushing and the key pin. When keys with molded plastic bushings are eased, the resilient plastic material will allow the wood to be compressed and the side walls of the plastic bushing tend to return to their previous position lying lightly against the metal key pin, thus continuing their gentle cushion action against the key pin.

It may therefore be seen that the invention provides a bushing which is not susceptible to appreciable changes when exposed to extremes of humidity and environmental temperatures. The result of such a construction is lower keyboard cost with no loss in level of performance and the elimination of manufacturing problems inherent in the materials and equipment used for traditional cloth bushings.

We claim:

1. A key and key pin bushing assembly for use in a musical keyboard instrument, including in combination, a wooden key shank having an opening therein, a resilient key pin bushing comprising a hollow tubular body having a plurality of ridges spaced axially along the outer surface of said body to form grooves therebetween, each of said ridges extending at least partially along a cross sectional periphery of said body, said bushing being disposed in said opening in said key shank, and a plurality of glue nubs bonded to the interior walls of said opening in said key shank and disposed in said grooves between said ridges to mechanically hold said key pin bushing in said opening.

2. A key and key pin bushing assembly for a musical keyboard instrument, including in combination, an elongated wooden key shank having a cylindrical opening therein of generally oval cross section, a plastic key pin bushing comprising a hollow cylindrical body of generally oval cross section having oppositely disposed relatively narrow sides and oppositely disposed relatively Wide sides and conforming with the shape of said opening in said key shank, said bushing having an outwardly extending Eflange portion at one end of said body and a plurality of transverse portions on each of said narrow sides spaced axially on the outer surface of said body to form a groove there'between, the outer extremities of said portions engaging the wall of said opening, and a plurality of glue nubs bonded to the narrow side wall .portions of said opening in said key shank and disposed in said grooves on said bushing to mechanically hold said bushing in said opening.

3. A plastic key pin bushing for a musical instrument key having a shank with an opening extending therein from one side of the shank and with nubs extending inwardly from the wall of the opening, said bushing including a hollow tubular body of resilient, low friction plastic having an outwardly extending flange portion at one end thereof, said body having grooves in the outside surface thereof shaped to receive the nubs in the opening in the key shank, so that the bushing is held in position in the key shank substantially entirely by the engagement of said flange portion with the one side of the key shank and by the mechanical interlock between said grooves and the nubs on the key shank.

4. A plastic key pin bushing for a musical instrument key having a shank with an opening of oval cross section extending therein, from one side of the shank and with nubs extending inwardly from the opposite end walls of the opening, said bushing including a hollow tubular body of oval cross section made of resilient, low friction plastic having an outwardly extending flange portion at one end thereof, said body having grooves in opposite outside end surfaces thereof shaped to receive the nubs in the opening in the key shank, so that the bushing is held in position in the key shank by the engagement of said flange portion with the one side of the key shank and the mechanical interlock of said grooves with the nubs on the key shank.

5. A plastic key pin bushing for a musical instrument key having a shank with an opening therein and with nubs extending inwardly from the wall of the opening on opposite sides, said bushing including a hollow tubular body made of resilient, low friction plastic having an outwardly extending flange portion at one end thereof, said body having portions in the opposite outside surfaces thereof grooves shaped to receive the nubs in the opening in the key shank, so that the bushing is held in position in the key shank by the mechanical interlock of said grooves with the nubs on the key shank.

6. The method of providing a key pin bushing for the key pin opening in the wooden key shank of a musical instrument key, such method including the steps of, molding from resilient, low friction, plastic material a resilient tubular plastic key pin bushing having an outwardly extending flange portion at one end and ridge portions on the outer surface of the tubular bushing forming grooves therebetween, placing the bushing in the opening in the key shank with the flange thereof engaging the shank, providing a liquid glue that adheres to the wooden key shank and does not substantially adhere to the plastic bushing in the opening in the key shank about the bushing, and allowing the glue to harden to form nubs secured to the inner wall of the opening and within the grooves of the bushing, whereby the bushing is held within the key shank by the mechanical interlock between the grooves of the resilient bushing and the nubs on the key shank.

7. The method of providing a key pin bushing for a musical instrument key having a wooden key shank with a key pin opening therein, such method including the steps of, molding from resilient, low friction, plastic material a tubular plastic key pin bushing having an outwardly extending flange portion at one end and grooves on opposite outer surfaces of the tubular bushing, placing the bushing in the opening in the key shank with the flange thereof engaging the shank, providing glue which adheres to the wooden key shank in the opening in the shank about the bushing, allowing the glue to harden to form nubs on the inner walls of the opening and within the grooves of the bushing, whereby the bushing is References Cited by the Examiner UNITED STATES PATENTS 316,023 4/1885 Ellis 84434 2,815,253 12/1957 Spriggs 308-238 3,008,779 11/ 1961 Spriggs 308-438 3,033,624 5/1962 Biesecker 308238 3,120,146 2/1964 Stiles 84-433 3,173,329 3/ 1965 Camillucci 84434 FOREIGN PATENTS 545,898 8/1922 France,

926,003 3/ 1947 France.

4,298 9/ 1881 Great Britain.

139,901 3/ 1920 Great Britain.

References Cited by the Applicant UNITED STATES PATENTS 669,729 3/ 1901 Hedgeland. 927,945 7/ 1909 Cheney. 1,813,751 7/1931 Malcolm.

LOUIS I. CAPOZI, Primary Examiner.

LEO SMILOW, Examiner.

CHARLES M. OVERBEY, Assistant Examiner. 

1. A KEY AND KEY PIN BUSHING ASSEMBLY FOR USE IN A MUSICAL KEYBOARD INSTRUMENT, INCLUDING IN COMBINATION, A WOODEN KEY SHANK HAVING AN OPENING THEREIN, A RESILIENT KEY PIN BUSHING COMPRISING A HOLLOW TUBULAR BODY HAVING A PLURALITY OF RIDGES SPACED AXIALLY ALONG THE OUTER SURFACE OF SAID BODY TO FORM GROOVES THEREBETWEEN, EACH OF SAID RIDGES EXTENDING AT LEAST PARTIALLY ALONG A CROSS SECTIONAL PERIPHERY OF SAID BODY, SAID BUSHING BEING DISPOSED IN SAID OPENING IN SAID KEY SHANK, AND A PLURALITY OF GLUE NUBS BONDED TO THE INTERIOR WALLS OF SAID OPENING IN SAID KEY SHANK AND DISPOSED IN SAID GROOVES BETWEEN SAID RIDGES TO MECHANICALLY HOLD SAID KEY PIN BUSHING IN SAID OPENING. 